Software Defined Radios 長庚電機通訊組 碩一 張晉銓 指導教授 : 黃文傑博士

Outline Multirate signal processing Sample rate conversion principle Decimation Interpolation Conclusions

Multirate signal processing The implementation of a digital signal processing application using variable sampling rates is called Multirate signal processing It is beneficial to alter the sampling rate used at different stages of the system Improve flexibility of a software radio (ADC). Synchronized Transmitter design

Sample rate conversion principle Downsampled to a lower sampling rate or upsampled to a higher sampling rate The sampling rate conversion can be thought of as the time-varying filter h(n,m) The factors I an D are the interpolation and decimation factors

Decimation (1/2)

Decimation (2/2)

Interpolation This process can be used for matching sampling rates between two systems.

Interpolation (zero-insertion )

I=4

Interpolation (zero-order-hold )

Interpolation (FFT expansion) DFT and IDFT

Interpolation (FFT expansion) Rayleigh fading envelop

Interpolation (FFT expansion)

Conclusions Noble Identities Non-Integer-rate conversion Sampling rate conversion by stages Cascaded integrator comb filter

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